Question

A hypothetical metal (W) has a body centered cubic crystal structure. Using a metallic radius of 139 pm for the W atom, calculate the density of W in grams per cubic centimeter. (1pm=10-12m) (Atomic weight of W is 183.84 g/mol)

Answer 1

Using formula, ZXM Density a3 x NA ...... (1) Where, z is number of atoms per unit cell Mis Atomic weight, a is edge length, NA is Avogadro number. Substitute following values in equation (1), M = 183.84 g/mol; a = 139 pm = 139 x 10-12 m = 139 x 10-12 x 102 cm = 139 x 10-10 cm; NA= 6.022 x 1023 mol and z = 2 (for BCC) 2 x 183.84 mol Density (139 x 10-10 cm)2 x 6.022 x 1023 (mol) Density = 227.34 g/cm3

Answer:

Density = 227.34 g/cc.

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